What is the role of a voltage regulator in an aircraft electrical system?

• A. It maintains the output voltage from the alternator at a constant level to protect electrical equipment.
• B. It increases battery capacity.
• C. It controls the fuel flow to the engine.
• D. It monitors cabin pressure.

Answer: (A)

A voltage regulator keeps the alternator’s output steady so the electrical system sees a constant voltage, protecting equipment from voltage swings. It monitors the bus voltage and adjusts the generator’s field current to hold the nominal system voltage (usually around 28 volts DC in most aircraft). When load increases and voltage tends to drop, the regulator increases field current to raise output. When load decreases or speed changes and voltage tends to rise, it decreases field current to prevent overvoltage. The battery mainly provides power when the generator isn’t producing or during transients, but the regulator’s job is to stabilize output, not to boost battery capacity. The other options describe functions outside electrical regulation (fuel flow, cabin pressure), so they aren’t relevant here.